London — Seven men have been arrested on suspicion of terrorism offenses in Britain after weapons were found in a vehicle stopped on a motorway, police said on Friday, as security forces are on high alert ahead of the London Olympics.

The vehicle was pulled over in a routine stop on the M1 motorway in South Yorkshire, northern England, on Saturday and impounded on suspicion of the driver having no insurance.

Firearms, other weapons and other unspecified material were later found inside which prompted police to trace and arrest the driver, passenger, and other suspects.

"As soon as the items were discovered in the impounded vehicle, our priority was to protect the public by pursuing and arresting those we believed to be involved," said Detective Chief Superintendent Kenny Bell, Head of the West Midlands region's Counter Terrorism Unit.

A police source said there was nothing to suggest any link to the Olympics, which start in three weeks' time.

Six men, all aged in their 20s and from the city of Birmingham in central England, were arrested on Tuesday and Wednesday, and a 43-year-old from northern England was held on Thursday, all on suspicion of the commission, preparation, or instigation of acts of terrorism.

There were no further details about what the men were suspected of planning or the weapons found.

The news came a day after police in London arrested five men and a woman on suspicion of planning terrorism attacks, although officers said this were not linked to the Olympics.

The police source said the two operations were not linked.

Armed police also closed both carriageways of the M6 motorway near Birmingham for four hours on Thursday after reports of a man acting suspiciously on a coach heading to London.

It later emerged the alert was caused by someone using an electronic cigarette on board.

London Olympics anxiety

Britain has spent millions of pounds beefing up security in preparation for the Olympics and last month Jonathan Evans, head of Britain's domestic intelligence agency MI5, warned the Games presented an attractive target.

The national threat level is assessed at "substantial" - meaning an attack is a strong possibility - but that is one notch lower than it has been for most of the years following the July 2005 suicide bomb attacks in London which killed 52 people.

Security chiefs have repeatedly said they have no intelligence that the Olympics are being targeted.

However as the Games approach, commentators have suggested heightened vigilance could lead to an increase in the number of arrests.

David Anderson, Britain's Independent Reviewer of Terrorism Legislation, has said he would be watching the police carefully to check there was no over-reaction.

"We have a lot of people in intelligence agencies manning their desks, having their leave cancelled, and no doubt there will be a temptation for people to use that time as the Olympics become closer to arrest people," he said in an interview with the Muslim News newspaper. "I am watching like a hawk."